Engineering Board Exam Reviewer · Sequences and Series · medium
Determine the value of x, so that x, 2x+4, 10x-4 will be a geometric progression.
- 2
- 4
- 5
- 6
Answer
B. 4
Solution
(2x+4)2 = x(10x-4) leads to 3x2-10x-8=0, which factors to give x=4 or x=-2/3. Since a positive integer is expected, x = 4.
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